The cutting assemblies of the known large headers of plant-cutting machines (e.g., combine, windrower) are typically driven by an oscillating drive, which can include, but is not limited to, an eccentric shaft on a rotating hub, a wobble drive, or a similar well-known commercially-available device. A cutting assembly is typically supported by a flexible cutterbar that spans the width of the opening of the crop harvesting header. The cutterbar is typically supported by arms that extend transverse to the cutterbar. Unfortunately, the weight of the cutting assembly is not uniformly distributed across the cutting width of the harvesting header, possibly causing bowing of the cutterbar, and the cutting assembly, resulting in uneven cutting height of the plant, as well as other undesirable results.
In response, Applicant has made great strides in this area through the use of a torsion device having elastic material, such as disclosed in U.S. Pat. No. 8,051,633, titled Cutterbar Adjustment Support For A Harvesting Header. However, further improvements are needed, such as maintaining performance while extending the service life of the elastic material.
What is needed is a system that provides substantially uniform support along the length of the cutting assembly by permitting selective adjustment of the forces the arms provide to the cutterbar, while maintaining performance and extending the service life of the system.